Documents of value within the terms of the invention can be bank notes identification documents, check cards, credit cards, but also share certificates, deeds, stamps, checks, admission tickets, tickets, flight tickets, identity cards, visa stickers and the like, as well as labels, seals, packagings or other elements. The simplifying designation “document of value” will hereinafter therefore always include documents of the stated type.
It is known from the state of the art to equip documents of value with security elements, such as security strips or also security threads, which contain magnetic material. The magnetic material therein can be applied on the security element either continuously or only in some regions, for example in the form of a coding. To magnetically code a security thread there is used for example a certain sequence of magnetic and non-magnetic regions that is characteristic of the type of document of value to be secured. Moreover it is known to use different magnetic materials for a coding, for example with different coercive field strength.
In the magnetic codings known so far for example two magnetic materials of different coercive strength are used, from which two types of magnet bits are formed. Along the magnetic coding the magnetic bits of different coercive strength are spaced apart from each other, e. g. separated by non-magnetic material.
For checking security elements by machine that have a magnetic coding along their longitudinal direction it is necessary that the magnetic coding can be detected upon different transport directions of the security element relative to the magnetic sensor. This is to be ensured in particular upon a transport of the security element parallel to the direction of the magnetic coding. In this measurement geometry it is difficult with regard to measuring technology to detect the magnetic regions of different coercive strength separately from each other in the magnetic codings known so far. By spacing the adjacent magnetic bits further magnetization steps and consequently further magnetic signals are added, which can overlap strongly. This is problematic particularly in conventional magnetic sensors, which are not suitable for distinguishing the magnetic regions of different coercive strength.
It is therefore the object of the invention to specify a magnetic coding with magnetic materials of different coercive strength for a security element in which the magnetic coding can be measured reliably also in the measurement geometry when the security element is transported along the magnetic coding.
It is furthermore an object of the invention to provide a security element, a document of value with the security element, as well as a measurement setup and a method for checking the document of value.